France's First Lady Carla Bruni has criticized Italian Prime Minister Silvio Berlusconi for joking about US President-elect Barack Obama's "suntan", and said she was glad to have given up her Italian citizenship.

"When I hear Silvio Berlusconi ... joke about the fact that Obama is always tanned, it feels strange to me," she told le Journal du Dimanche newspaper in an interview published on Sunday. "Some people will no doubt put it down to humor, but often I find that I am pleased to have become French," she said.

The Italian-born model and pop singer became a French national and gave up her Italian citizenship after she married French President Nicolas Sarkozy in February.

Berlusconi had said on Thursday that Obama, who will be the first African-American US president, was "handsome, young and also suntanned".

Italy's left-wing opposition parties accused Berlusconi of bringing discredit on the nation with the quip. "He forgets that his statements cast doubt on the image of our country in the world," said Dario Franceschini, member of parliament for the center-left Democratic Party. Berlusconi responded by calling them "imbeciles" with no sense of humor.

Meanwhile French politicians and celebrities had published a petition calling for positive discrimination in favour of people from ethnic minorities. The program "Oui, nous pouvons!" ("Yes, we can!") demands concrete political change to make the French ideal of equality reality for the millions of immigrants living in France.

Bruni-Sarkozy did not sign the petition because of her status as wife of the president but she said she supported it in every respect.

"My husband is not Obama. But the French voted for the son of a Hungarian immigrant, whose father had an accent, whose mother was of Jewish origin, and his stance has always been to say that he's French although he comes from somewhere else."

She continued: "He doesn't look like the traditional French elite but that didn't stop him. And, personally, I don't correspond to the profile of a first lady! I'm an artist, born Italian...Of course, we are, him and me, of European stock, and that's easier."

She said she hoped the "Obama effect" would also change French society.